PyQt5: Create semi-transparent window with non-transparent children

Question

I want to create a fullscreen window with semitransparent background, but fully visible children widgets (kind of overlay effect).

Here\'s what I have so far:

Answer 1

Ok, while is seems not to work with the available flags you can still use Qt.WA_TranslucentBackground because it is possible to draw a semitranparent rect on that transparency.

Derive your mainwindow from QMainWindow and use that class instead.

Apply self.setAttribute(Qt.WA_TranslucentBackground, True) to that class

Implement the paintEvent of your mainwindow class like this (similar, might contain errors, but the principle should work):

QPixmap canvas(rect())

canvas.fill(Qt.transparent) # fill transparent (makes alpha channel available)

QPainter p(canvas)           # draw on the canvas
p.setOpacity(0.3)
p.setBrush(QBrush(Qt.white)) # use the color you like
p.setPen(QPen(Qt.transparen))

p.drawRect(rect()) # draws the canvas with desired opacity

p.start(self)      # now draw on the window itself
p.drawPixmap(rect(), canvas)